Planet Formation is Child's Play

An artist's rendition of the 1-million-year-old star system UX Tau A, located approximately 450 light-years away. Observations from NASA's Sptizer Space Telescope showed a gap in the dusty disk swirling around the system's central star. Astronomers suspect that the formation of one or multiple planets carved the space in this disk.Credit: NASA

Astronomers
think they have found the two youngest solar systems ever detected, where
infant planets could be sweeping up dust and creating voids in protoplanetary
disks 450 light-years from Earth.

NASA's
Spitzer Space Telescope observed the ring-like gaps, which could signal the
earliest signs of rocky planet formation around two young stars located in the
constellation Taurus—UX Tau A and LkCa 15. Both stars are about 1 million years
old, which is 10 times younger than other known
planet-forming systems.

"Previously,
astronomers were seeing holes at the centers of protoplanetary disks," said
Catherine Espaillat, an astronomer at the University of Michigan in Ann Arbor. Such holes are typically thought to be caused by photoevaporation, or stars burning
dust away into light energy.

But instead
of central holes, Espaillat's team saw ring-like gaps in the spinning planetary
materials.

"It's
more like a lane has been cleared within the disk. The existence of planets is
the most probable theory that can explain this structure," she said, as
the lanes are likely too distant from the star to photoevaporate.

The idea is
similar to touching a dusty record as it rotates, clearing a ring in the mat of
particles; planets, however, use their growing gravity to sweep up the dust.

The Dec. 1
issue of Astrophysical Journal Letters will detail Espaillat and her
colleagues' findings about the infant solar systems, which they said could help
explain our own planet's past.

"We
are looking for our history," said University of Michigan astronomer Nuria Calvet, who worked with Espaillat on the research.
"We are looking for the history of solar systems, trying to understand how
they form."